
// This file defines the type used to provide sources for NotificationService
// notifications.

#ifndef __notification_source_h__
#define __notification_source_h__

#pragma once

#include "base/basic_types.h"

// Do not declare a NotificationSource directly--use either
// "Source<sourceclassname>(sourceclasspointer)" or
// NotificationService::AllSources().
class NotificationSource
{
public:
    NotificationSource(const NotificationSource& other);
    ~NotificationSource();

    // NotificationSource can be used as the index for a map; this method
    // returns the pointer to the current source as an identifier, for use as a
    // map index.
    uintptr_t map_key() const { return reinterpret_cast<uintptr_t>(ptr_); }

    bool operator!=(const NotificationSource& other) const
    {
        return ptr_ != other.ptr_;
    }
    bool operator==(const NotificationSource& other) const
    {
        return ptr_ == other.ptr_;
    }

protected:
    explicit NotificationSource(const void* ptr);

    // Declaring this const allows Source<T> to be used with both T = Foo and
    // T = const Foo.
    const void* ptr_;
};

template<class T>
class Source : public NotificationSource
{
public:
    // TODO(erg): Our code hard relies on implicit conversion
    Source(const T* ptr) : NotificationSource(ptr) {} // NOLINT
    Source(const NotificationSource& other) // NOLINT
        : NotificationSource(other) {}

    T* operator->() const { return ptr(); }
    // The casts here allow this to compile with both T = Foo and T = const Foo.
    T* ptr() const { return static_cast<T*>(const_cast<void*>(ptr_)); }
};

#endif //__notification_source_h__